Definitely replace it with a yellow top or other upgraded battery...when it dies after 4 years of faithful service.

 

Hmmm. I'll have to drop it off at the dealer then. I really dont have any major aftermarket electronic stuff other than a radar dectector which I unplug (it has battery run down protection in it anyway). I have already had one bad delco battery so this may be #2. The reason i was thinking my onstar was active while the truck is off is that last summerI was getting vehicle diag reports but didn't drive the truck for 3 months. So I was thinking that the truck was calling mother ship at some point to send a status.

 

OnStar does call the truck oncea month to get the engine diag.

 

They can also unlock your doors when it is off, so at some level the OnStar system has to be operating 24/7. I would say at a minimum its equal to a charging phone but i would guess its more like a constant powered on cell phone (not the new super efficient ones either)

 

Disconect the + terminal on the battery and check the amp draw with a VOM with everything turned off.

Anything over .5 amps is to high and will drain the battery within a week.